乱石包高速远程滑坡流态化运动模式及摩擦热效应研究

Research on the fluidized propagation and frictional heating effect of the Luanshibao rock avalanche

高速远程滑坡动力学机制一直是国际滑坡领域研究的热点挑战性难题,聚焦这一科学问题,以乱石包高速远程滑坡为研究对象,借助MatDEM软件,开展了滑坡运动演化全过程有效模拟,从细观角度进一步论证滑坡的流态化运动模式与摩擦热效应。研究发现:(1)滑体运动速度呈现明显的垂向分带特征,底部为速度较低的强剪切带,中上部为速度较高的主滑体;(2)滑坡质心最大运动速度为33.3 m/s,最大水平和垂直位移分别为1469.9和374.1 m,等效摩擦因数为0.255;(3)摩擦能占总能量损失的44.3%,主要集中于流通区的强剪切带,与之相应,流通区滑体与下伏层之间的铲刮裹挟作用明显高于堆积区;(4)滑体运动过程中所产生的摩擦能可使流通区剪切带颗粒平均升温约64℃,产生摩擦热效应;(5)滑体等效摩擦因数在流通区和堆积区中后部呈低值分布,流通区强烈动量传递作用、铲刮裹挟效应和摩擦热效应的出现,应为摩擦因数降低的主要原因。该数值模拟结果与现场调查所得滑坡特征有较好的一致性,有助于滑体流态化运动过程和摩擦热现象的定量揭示,对高速远程滑坡运动学和动力学机制研究具有重要科学价值。

Rock avalanche dynamics is always a hot and challenging issue in the field of landslide.Focusing on this issue,the Luanshibao rock avalanche is chosen as an example with its whole propagation process being simulated by MatDEM,to further illustrate its fluidized propagation and frictional heating effect from a mesoscopic point of view.It is reached that:(1)The velocity of the sliding mass presents an obvious vertical zoning feature with the bottom forming an intensive shearing zone characterized by lower velocity and the upper part characterized by higher velocity.(2)The maximum velocity of the mass center is 33.3 m/s.Its horizontal runout and vertical drop are 1469.9 and 374.1 m,respectively,with the equivalent friction coefficient being 0.255.(3)Frictional energy occupies 44.3%of the total loss of the potential energy,which mainly distributes along the basal facies in the translation zone.Correspondingly,the entrainment effect in the translation zone is obviously higher than that in the accumulation zone.(4)The frictional energy generated in the propagation can cause the basal facies to rise by 64℃with frictional heating effects generated.(5)In the translation zone and the rear part of the accumulation zone,the equivalent friction coefficient displays in low values,which is attributed to the coupling effect of momentum transfer,entrainment effect and frictional heating effect.The simulated results have a good consistency with the field investigated data,which is conducive to the revealing on its propagation mode and frictional heating effect.The simulated results can provide significant scientific value for rock avalanche kinematics and dynamics.